Gold-based alloy electric contact piece and preparation method thereof

Abstract

The invention discloses a gold-based alloy electric contact piece and a preparation method thereof, and belongs to the technical field of precious metal alloy materials. The gold-based alloy electric contact piece comprises, by mass, 25%-30% of palladium, 15%-20% of silver, 1%-5% of tin and the balance gold. According to the gold-based alloy electric contact piece, the gold-based alloy components and the preparation method are synergistically optimized, so that the mechanical property of the gold-based alloy electric contact piece is better balanced, meanwhile, the conductivity and the wear resistance of the gold-based alloy electric contact piece are effectively improved, the overall comprehensive performance of the gold-based alloy electric contact piece reaches a better level, and the use requirements of severe working conditions are met.

Description

Technical Field

[0001] This invention belongs to the field of precious metal alloy materials technology, and relates to a gold-based alloy electrical contact sheet and its preparation method. Background Technology

[0002] With the rapid development of high-speed rail, aerospace, precision instruments and other fields, higher requirements are being placed on the performance of electrical contact materials operating under harsh conditions such as high temperature, high speed and high load. These materials not only need to have excellent wear resistance and low resistivity, but also good tensile strength and plasticity.

[0003] Noble metal alloys, especially gold-based alloys, hold an irreplaceable position in the field of high-precision and high-reliability electrical contacts. However, traditional gold-based wear-resistant materials (such as Au-Ag-Cu and Au-Ni systems) mainly rely on solid solution strengthening or the introduction of coarse second phases to improve hardness and thus wear resistance. Under high temperature or high load conditions, wear resistance is prone to a sharp decline due to coarsening of precipitates or interface detachment. Existing technologies have attempted to delay material softening by adding high-melting-point metals (such as W and Mo), but this often leads to poor cold working properties and a significant increase in resistivity, making it difficult to achieve a comprehensive optimization of mechanical properties, wear resistance, and electrical conductivity.

[0004] Therefore, it is necessary to provide a gold-based alloy electrical contact sheet and its preparation method. Through the synergistic optimization of alloy composition and preparation method, a gold-based alloy electrical contact sheet with excellent mechanical properties, wear resistance and conductivity can be effectively obtained. Summary of the Invention

[0005] To overcome the problems in the prior art, this invention synergistically optimizes the composition and preparation method of gold-based alloys, constructing a strong and tough coupling structure of high-density nanoscale intermetallic compounds and dislocation networks in the alloy matrix, thereby enabling the gold-based alloy electrical contact sheet to have good mechanical properties, high wear resistance, and high conductivity.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: The present invention provides a gold-based alloy electrical contact sheet, wherein the gold-based alloy electrical contact sheet comprises, by mass percentage: palladium: 25%-30%, silver: 15%-20%, tin: 1%-5%, and the balance being gold.

[0007] In another aspect, the present invention provides a method for preparing the above-mentioned gold-based alloy electrical contact sheet, the method comprising the following steps: (1) Palladium, silver, tin and gold raw materials are mixed and smelted in an inert gas protective environment, and then cast to obtain ingots.

[0008] (2) Perform solution treatment on the ingot in step (1).

[0009] (3) The ingot after solution treatment in step (2) is cold-forged multiple times to obtain a plate.

[0010] (4) In an inert atmosphere, the plate in step (3) is hot rolled in multiple passes to obtain a hot rolled billet. After each hot rolling pass, the hot rolled part is kept warm.

[0011] (5) The hot-rolled billet in step (4) is annealed in an inert atmosphere to obtain an annealed billet.

[0012] (6) After the annealed billet in step (5) is subjected to multiple cold rolling and aging treatments, a sheet is obtained. During the multiple cold rolling process, a low-temperature tempering is performed after every 5-8 rolling passes. The aging treatment is carried out in an inert atmosphere protection environment.

[0013] (7) The sheet material in step (6) is subjected to surface treatment to obtain a gold-based alloy electrical contact sheet.

[0014] Preferably, in step (1), the melting temperature is 1300-1400℃ and the melting time is 10-15min.

[0015] Preferably, in step (2), the solution temperature is 1140-1160℃, the holding time is 3.5-4h, and after holding, water quenching is performed with a cooling rate ≥200℃ / s.

[0016] Preferably, in step (3), the deformation amount of a single cold forging is ≤5%, and the cumulative deformation amount of cold forging is 50-75%.

[0017] Preferably, in step (4), the plate is heated to 700-750℃, held for 40-60 minutes, and then hot rolled while maintaining the temperature. After each hot rolling pass, the plate is held at 700-750℃ for 5-10 minutes. The deformation of a single pass in multi-pass hot rolling is ≤5%, and the total deformation of multi-pass hot rolling is 40-60%.

[0018] Preferably, in step (5), the annealing temperature is 900-1000℃, the holding time is 15-20min, and after holding, the water is quenched with a cooling rate ≥200℃ / s.

[0019] Preferably, in step (6), the single-pass deformation of the multi-pass cold rolling is 3-5%, the cumulative deformation is 50-75%, the low-temperature tempering temperature is 150-200℃, and the tempering time is 10-20min.

[0020] Preferably, in step (6), the aging treatment temperature is 600-800℃, the holding time is 50-60min, and after holding, the water is quenched with a water quenching rate ≥200℃ / s.

[0021] Preferably, in step (7), the surface treatment process includes: firstly, using saturated saline or saturated hydrochloric acid as the electrolytic polishing solution to electropolish the sheet, with the electrolytic polishing temperature being 15-25℃ and the current density controlled at 3-5A / dm² according to the sheet area. 2 Then, ultrasonic cleaning and vacuum drying are performed in sequence.

[0022] Ultrasonic cleaning and vacuum drying can be performed using conventional methods.

[0023] The beneficial effects of this invention are: 1. The preparation process of this invention can transform the disordered solid solution phase in the alloy into a multi-element ordered intermetallic compound phase (such as Pd3Sn, Pd2Sn, PdSn), and synergistically promote the ordering of the alloy with the Sn element, thereby effectively improving the wear resistance, tensile strength, conductivity and other properties of the electrical contact piece.

[0024] 2. In the gold-based alloy of the present invention, there are uniformly distributed multi-metallic compound precipitates with a size of 20-50 nm, the proportion of precipitates inside the grains is more than 20%, and there are precipitates with a size of 50-300 nm at the grain boundaries. The hardness of the gold-based alloy electrical contact sheet of the present invention can reach more than 300 HV0.1, the tensile strength can reach more than 862 MPa, the elongation can reach more than 20%, the friction and wear coefficient can reach less than 0.53, and the room temperature resistivity can be maintained below 25 μΩ·cm. Attached Figure Description

[0025] Figure 1 These are comparison graphs showing the resistance changes of the electrical contact sheets prepared in Examples 1-3 and Comparative Examples 1 and 2 of the present invention. Figure 2 These are comparison diagrams showing the hardness changes of the electrical contact sheets prepared in Examples 1-3 and Comparative Examples 1 and 2 of the present invention. Figure 3 These are stress-strain comparison diagrams of the electrical contact sheets prepared in Examples 1-3 and Comparative Examples 1 and 2 of the present invention. Figure 4 This is a microstructure diagram of the electrical contact sheet prepared in Example 3 of the present invention; Figure 5 This is a comparison chart of the friction coefficients of the electrical contact sheets prepared in Examples 1-3 and Comparative Examples 1 and 2 of the present invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0027] In Examples 1-5, the composition of the gold-based alloy electrical contact piece is shown in Table 1.

[0028] Table 1 Example 1 This embodiment prepares a gold-based alloy electrical contact sheet according to the following steps: (1) Ingredients: Weigh the raw materials of metal Pd, Ag, Sn and Au according to the composition of gold-based alloy shown in Table 1 (the purity of the raw materials shall not be less than 99.95%).

[0029] Since Sn is relatively volatile, an additional 0.2-0.3% of metallic Sn can be weighed out when preparing the ingredients.

[0030] Before smelting, use acetone or alcohol to ultrasonically clean the metal raw materials to remove oil and impurities from the surface of the metal raw materials. The ultrasonic cleaning time is generally no less than 10 minutes. After cleaning, wash off the acetone or alcohol with deionized water and then let it air dry.

[0031] (2) Melting: High-purity argon gas (argon purity not less than 99.999%) is introduced into the vacuum high-frequency induction furnace to form an inert atmosphere protective environment. The raw material is placed in a graphite crucible and placed in the furnace cavity of the vacuum high-frequency induction furnace. The raw material is heated to 1400℃ and melted for 10 minutes. Then, the melt is poured into a water-cooled copper mold to obtain a square ingot with a thickness of 20mm.

[0032] (3) After heating the ingot to 1150℃ and holding it for 4 hours, water quench it and control the cooling rate to be no less than 200℃ / s.

[0033] (4) At room temperature, the solution-treated ingot is subjected to multiple cold forging passes, with the deformation per pass controlled at 5% and the cumulative deformation at 60%, to obtain a plate with a thickness of 8mm.

[0034] (5) In an argon-protected environment, the plate is heated to 700°C and held for 1 hour. Then, the plate is hot rolled for the first time at this temperature. After the first hot rolling, the plate is put back into the furnace and held at 700°C for 5 minutes before being taken out for rolling. This process is repeated for subsequent hot rolling and holding cycles. The deformation amount per pass is controlled to be 5%, and the total deformation amount is 50%, to obtain the hot-rolled billet.

[0035] (6) In an argon-protected environment, the hot-rolled billet is heated to 1000℃, held for 15 minutes and then water-quenched. The cooling rate is controlled to be ≥200℃ / s to obtain the annealed billet.

[0036] (7) At room temperature, the annealed billet is rolled in multiple passes, and the deformation per pass is controlled to be 5%. After every 5 passes of rolling, the cold-rolled part is heated to 170°C and held for 15 minutes. The cycle is carried out in the order of single-pass cold rolling-low temperature tempering until the cumulative deformation is 75%, and a sheet with a thickness of 1.0±0.2mm is obtained.

[0037] (8) In an argon-protected environment, heat the sheet to 600°C, keep it at that temperature for 1 hour, and then quench it with water, controlling the cooling rate to be ≥200°C / s.

[0038] (9) Use saturated saline solution as the electrolytic polishing solution at 20℃ and 4A / dm³. 2 Under current density conditions, the aged sheet is electrolytically polished until the surface roughness Ra of the electrical contact sheet is ≤0.2μm. Then, the sheet is ultrasonically cleaned and vacuum dried to obtain a gold-based alloy electrical contact sheet.

[0039] The performance of the electrical contact piece prepared in this embodiment was tested, and the results are as follows: The electrical contact sheet prepared in this embodiment has a hardness of 314.6HV0.1, a room temperature tensile strength of 761MPa, a room temperature resistivity of 24.5μΩ·cm, and a friction wear coefficient of 0.516.

[0040] Example 2 This embodiment prepares a gold-based alloy electrical contact sheet according to the following steps: (1) Ingredients: Weigh the raw materials of metal Pd, Ag, Sn and Au according to the composition of gold-based alloy shown in Table 1 (the purity of the raw materials shall not be less than 99.95%).

[0041] Since Sn is relatively volatile, an additional 0.2-0.3% of metallic Sn can be weighed out when preparing the ingredients.

[0042] Before smelting, use acetone or alcohol to ultrasonically clean the metal raw materials to remove oil and impurities from the surface of the metal raw materials. The ultrasonic cleaning time is generally no less than 10 minutes. After cleaning, wash off the acetone or alcohol with deionized water and then let it air dry.

[0043] (2) Melting: High-purity argon gas (argon purity not less than 99.999%) is introduced into the vacuum high-frequency induction furnace to form an inert atmosphere protective environment. The raw material is placed in a graphite crucible and then placed in the furnace cavity of the vacuum high-frequency induction furnace. The raw material is heated to 1350°C and melted for 13 minutes. After that, the melt is poured into a water-cooled copper mold to obtain a square ingot with a thickness of 20 mm.

[0044] (3) After heating the ingot to 1150℃ and holding it for 4 hours, water quench it and control the cooling rate to be no less than 200℃ / s.

[0045] (4) At room temperature, the solution-treated ingot is subjected to multiple cold forging passes, with the deformation per pass controlled at 5% and the cumulative deformation at 60%, to obtain a plate with a thickness of 8mm.

[0046] (5) In an argon-protected environment, the plate is heated to 700°C and held for 1 hour. Then, the plate is hot rolled for the first time at this temperature. After the first hot rolling, the plate is put back into the furnace and held at 700°C for 5 minutes before being taken out for rolling. This process is repeated for subsequent hot rolling and holding cycles. The deformation amount per pass is controlled to be 5%, and the total deformation amount is 50%, to obtain the hot-rolled billet.

[0047] (6) In an argon-protected environment, the hot-rolled billet is heated to 1000℃, held for 15 minutes and then water-quenched. The cooling rate is controlled to be ≥200℃ / s to obtain the annealed billet.

[0048] (7) At room temperature, the annealed billet is rolled in multiple passes, and the deformation per pass is controlled to be 5%. After every 5 passes of rolling, the cold-rolled part is heated to 170°C and held for 15 minutes. The cycle is carried out in the order of single-pass cold rolling-low temperature tempering until the cumulative deformation is 75%, and a sheet with a thickness of 1.0±0.2mm is obtained.

[0049] (8) In an argon-protected environment, heat the sheet to 700°C, keep it at that temperature for 1 hour, and then quench it with water, controlling the cooling rate to be ≥200°C / s.

[0050] (9) Use saturated saline solution as the electrolytic polishing solution at 25°C and 5A / dm³. 2 Under current density conditions, the aged sheet is electrolytically polished until the surface roughness Ra of the electrical contact sheet is ≤0.2μm. Then, the sheet is ultrasonically cleaned and vacuum dried to obtain a gold-based alloy electrical contact sheet.

[0051] The performance of the electrical contact piece prepared in this embodiment was tested, and the results are as follows: The electrical contact sheet prepared in this embodiment has a hardness of 320HV0.1, a room temperature tensile strength of 862MPa, a room temperature resistivity of 21.61μΩ·cm, and a friction wear coefficient of 0.513.

[0052] Example 3 This embodiment prepares a gold-based alloy electrical contact sheet according to the following steps: (1) Ingredients: Weigh the raw materials of metal Pd, Ag, Sn and Au according to the composition of gold-based alloy shown in Table 1 (the purity of the raw materials shall not be less than 99.95%).

[0053] Since Sn is relatively volatile, an additional 0.2-0.3% of metallic Sn can be weighed out when preparing the ingredients.

[0054] Before smelting, use acetone or alcohol to ultrasonically clean the metal raw materials to remove oil and impurities from the surface of the metal raw materials. The ultrasonic cleaning time is generally no less than 10 minutes. After cleaning, wash off the acetone or alcohol with deionized water and then let it air dry.

[0055] (2) Melting: High-purity argon gas (argon purity not less than 99.999%) is introduced into the vacuum high-frequency induction furnace to form an inert atmosphere protective environment. The raw material is placed in a graphite crucible and then placed in the furnace cavity of the vacuum high-frequency induction furnace. The raw material is heated to 1300℃ and melted for 15 minutes. After that, the melt is poured into a water-cooled copper mold to obtain a square ingot with a thickness of 20mm.

[0056] (3) After heating the ingot to 1150℃ and holding it for 4 hours, water quench it and control the cooling rate to be no less than 200℃ / s.

[0057] (4) At room temperature, the solution-treated ingot is subjected to multiple cold forging passes, with the deformation per pass controlled at 5% and the cumulative deformation at 60%, to obtain a plate with a thickness of 8mm.

[0058] (5) In an argon-protected environment, the plate is heated to 700°C and held for 1 hour. Then, the plate is hot rolled for the first time at this temperature. After the first hot rolling, the plate is put back into the furnace and held at 700°C for 5 minutes before being taken out for rolling. This process is repeated for subsequent hot rolling and holding cycles. The deformation amount per pass is controlled to be 5%, and the total deformation amount is 50%, to obtain the hot-rolled billet.

[0059] (6) In an argon-protected environment, the hot-rolled billet is heated to 1000℃, held for 15 minutes and then water-quenched. The cooling rate is controlled to be ≥200℃ / s to obtain the annealed billet.

[0060] (7) At room temperature, the annealed billet is rolled in multiple passes, and the deformation per pass is controlled to be 5%. After every 5 passes of rolling, the cold-rolled part is heated to 170°C and held for 15 minutes. The cycle is carried out in the order of single-pass cold rolling-low temperature tempering until the cumulative deformation is 75%, and a sheet with a thickness of 1.0±0.2mm is obtained.

[0061] (8) In an argon-protected environment, heat the sheet to 800°C, keep it at that temperature for 1 hour, and then quench it with water, controlling the cooling rate to be ≥200°C / s.

[0062] (9) Use saturated saline solution as the electrolytic polishing solution at 15°C and 3A / dm³. 2 Under current density conditions, the aged sheet is electrolytically polished until the surface roughness Ra of the electrical contact sheet is ≤0.2μm. Then, the sheet is ultrasonically cleaned and vacuum dried to obtain a gold-based alloy electrical contact sheet.

[0063] The performance of the electrical contact piece prepared in this embodiment was tested, and the results are as follows: The electrical contact sheet prepared in this embodiment has a hardness of 297.3HV0.1, a room temperature tensile strength of 637MPa, a room temperature resistivity of 21.91μΩ·cm, and a friction wear coefficient of 0.529.

[0064] Example 4 This embodiment prepares a gold-based alloy electrical contact sheet according to the following steps: (1) Ingredients: Weigh the raw materials of metal Pd, Ag, Sn and Au according to the composition of gold-based alloy shown in Table 1 (the purity of the raw materials shall not be less than 99.95%).

[0065] Since Sn is relatively volatile, an additional 0.2-0.3% of metallic Sn can be weighed out when preparing the ingredients.

[0066] Before smelting, use acetone or alcohol to ultrasonically clean the metal raw materials to remove oil and impurities from the surface of the metal raw materials. The ultrasonic cleaning time is generally no less than 10 minutes. After cleaning, wash off the acetone or alcohol with deionized water and then let it air dry.

[0067] (2) Melting: High-purity argon gas (argon purity not less than 99.999%) is introduced into the vacuum high-frequency induction furnace to form an inert atmosphere protective environment. The raw material is placed in a graphite crucible and then placed in the furnace cavity of the vacuum high-frequency induction furnace. The raw material is heated to 1350°C and melted for 13 minutes. After that, the melt is poured into a water-cooled copper mold to obtain a square ingot with a thickness of 20 mm.

[0068] (3) After heating the ingot to 1140℃ and holding it for 3.7h, water quench it and control the cooling rate to be no less than 200℃ / s.

[0069] (4) At room temperature, the solution-treated ingot is subjected to multiple cold forging passes, with the deformation per pass controlled at 3% and the cumulative deformation at 75%, to obtain a plate with a thickness of 5mm.

[0070] (5) In an argon-protected environment, the plate is heated to 750°C and held for 40 minutes. Then, the plate is hot rolled for the first time at this temperature. After the first hot rolling, the plate is put back into the furnace and held at 750°C for 7 minutes before being taken out for rolling. This cycle is repeated for subsequent hot rolling and holding. The deformation amount per pass is controlled to be 3%, and the total deformation amount is 60%, to obtain the hot-rolled billet.

[0071] (6) In an argon-protected environment, the hot-rolled billet is heated to 900°C, held for 20 minutes and then water-quenched. The cooling rate is controlled to be ≥200°C / s to obtain the annealed billet.

[0072] (7) At room temperature, the annealed billet is rolled in multiple passes, and the deformation per pass is controlled to be 3%. After every 7 passes of rolling, the cold-rolled part is heated to 200°C and held for 10 minutes. The cycle is carried out in the order of single-pass cold rolling-low temperature tempering until the cumulative deformation is 60%, and a sheet with a thickness of 0.8±0.2 mm is obtained.

[0073] (8) In an argon-protected environment, heat the sheet to 800°C, hold for 50 minutes and then quench it with water, controlling the cooling rate to be ≥200°C / s.

[0074] (9) Use saturated saline solution as the electrolytic polishing solution at 25°C and 5A / dm³. 2 Under current density conditions, the aged sheet is electrolytically polished until the surface roughness Ra of the electrical contact sheet is ≤0.2μm. Then, the sheet is ultrasonically cleaned and vacuum dried to obtain a gold-based alloy electrical contact sheet.

[0075] The electrical contact sheet prepared in this embodiment has similar performance to that in Example 1.

[0076] Example 5 This embodiment prepares a gold-based alloy electrical contact sheet according to the following steps: (1) Ingredients: Weigh the raw materials of metal Pd, Ag, Sn and Au according to the composition of gold-based alloy shown in Table 1 (the purity of the raw materials shall not be less than 99.95%).

[0077] Since Sn is relatively volatile, an additional 0.2-0.3% of metallic Sn can be weighed out when preparing the ingredients.

[0078] Before smelting, use acetone or alcohol to ultrasonically clean the metal raw materials to remove oil and impurities from the surface of the metal raw materials. The ultrasonic cleaning time is generally no less than 10 minutes. After cleaning, wash off the acetone or alcohol with deionized water and then let it air dry.

[0079] (2) Melting: High-purity argon gas (argon purity not less than 99.999%) is introduced into the vacuum high-frequency induction furnace to form an inert atmosphere protective environment. The raw material is placed in a graphite crucible and then placed in the furnace cavity of the vacuum high-frequency induction furnace. The raw material is heated to 1350°C and melted for 13 minutes. After that, the melt is poured into a water-cooled copper mold to obtain a square ingot with a thickness of 20 mm.

[0080] (3) After heating the ingot to 1160℃ and holding it for 3.5h, water quench it and control the cooling rate to be no less than 200℃ / s.

[0081] (4) At room temperature, the solution-treated ingot is subjected to multiple cold forging passes, with the deformation per pass controlled at 1% and the cumulative deformation at 50%, to obtain a plate with a thickness of 10 mm.

[0082] (5) In an argon-protected environment, the plate is heated to 730°C and held for 50 minutes. Then, the plate is hot rolled for the first time at this temperature. After the first hot rolling, the plate is put back into the furnace and held at 730°C for 10 minutes before being taken out for rolling. This process is repeated for subsequent hot rolling and holding cycles. The deformation amount per pass is controlled at 1%, and the total deformation amount is 40%, to obtain the hot-rolled billet.

[0083] (6) In an argon-protected environment, the hot-rolled billet is heated to 950°C, held for 17 minutes and then water-quenched. The cooling rate is controlled to be ≥200°C / s to obtain the annealed billet.

[0084] (7) At room temperature, the annealed billet is rolled in multiple passes, and the deformation per pass is controlled to be 1%. After every 8 passes of rolling, the cold-rolled part is heated to 150°C and held for 20 minutes. Then, the cycle is carried out in the order of single-pass cold rolling-low temperature tempering until the cumulative deformation is 50%, and a sheet with a thickness of 3±0.2mm is obtained.

[0085] (8) In an argon-protected environment, heat the sheet to 600°C, hold for 55 minutes, and then quench it with water, controlling the cooling rate to be ≥200°C / s.

[0086] (9) Use saturated saline solution as the electrolytic polishing solution at 25°C and 5A / dm³. 2 Under current density conditions, the aged sheet is electrolytically polished until the surface roughness Ra of the electrical contact sheet is ≤0.2μm. Then, the sheet is ultrasonically cleaned and vacuum dried to obtain a gold-based alloy electrical contact sheet.

[0087] The electrical contact sheet prepared in this embodiment has similar performance to that in Example 1.

[0088] Comparative Example 1 This comparative example uses the same method as Example 2 to prepare gold-based alloy electrical contact sheets, except that this comparative example does not undergo aging treatment.

[0089] The electrical contact sheet prepared in this comparative example has a hardness of 207HV0.1, a room temperature tensile strength of 455MPa, a room temperature resistivity of 31μΩ·cm, and a friction wear coefficient of 0.541.

[0090] Comparative Example 2 This comparative example uses the same method as Example 2 to prepare gold-based alloy electrical contact sheets, except that the aging treatment temperature in this comparative example is 500°C.

[0091] The electrical contact sheet prepared in this comparative example has a hardness of 254.67 HV0.1, a room temperature tensile strength of 584 MPa, a room temperature resistivity of 29.15 μΩ·cm, and a friction wear coefficient of 0.538.

[0092] Comparative Example 3 The gold-based alloy electrical contact sheet was prepared using the same method as in Example 2. The difference is that in step (7) of this comparative example, a low-temperature tempering was performed after each cold rolling pass.

[0093] In this comparative example, the low-temperature tempering frequency is too frequent. Frequent thermal cycling will hinder the effective accumulation of dislocations and the ordering process of nano-precipitates during cold rolling, which is not conducive to the formation of a stable high-density dislocation network and a uniform nano-precipitate structure. This will have a negative impact on the performance of the gold-based alloy electrical contact sheet.

[0094] Comparative Example 4 The gold-based alloy electrical contact sheet was prepared using the same method as in Example 2. The difference is that in step (5) of this comparative example, the hot rolling temperature was 800°C, and the sheet was kept warm at 800°C after each hot rolling pass.

[0095] In this comparative example, recrystallization caused by the high hot rolling temperature disrupted the original uniform and refined grain structure, resulting in a decrease in the performance of the gold-based alloy electrical contact sheet.

[0096] A comparison of Example 2 with Comparative Examples 1 and 2 shows that (as...) Figure 1 , 2 (3, 5) The electrical contact sheet of Example 2 has significant improvements in hardness, tensile strength and conductivity. Although the elongation of the electrical contact sheet of Example 2 is lower than that of Comparative Examples 1 and 2, the tensile strength of Example 2 can be effectively increased to 800 MPa and its elongation can be maintained above 20%, which is still at a relatively good level. Therefore, the electrical contact sheet of Example 2 has relatively excellent and balanced mechanical, wear-resistant and conductive properties.

[0097] A comparison of Examples 1-3 and Comparative Example 2 shows that the gold-based alloy is in the under-aging stage at 500℃, and its overall performance is still at a relatively poor level. As the aging temperature increases, the alloy exhibits obvious age-hardening behavior, which is due to the strengthening effect of discontinuous precipitates and fine grains. When the aging temperature exceeds 700℃, the hardness decreases, proving that above 700℃, the precipitates begin to coarsen, leading to a decrease in hardness. Therefore, when the aging temperature rises to 800℃, the hardness of the gold-based alloy electrical contact sheet decreases. As the temperature further increases, the precipitates will coarsen further, leading to a more severe decrease in hardness. Therefore, the present invention controls the aging temperature within a reasonable range, which is beneficial to keep the hardness of the gold-based alloy electrical contact sheet at a relatively excellent level.

[0098] A comparison of Examples 1-3 and Comparative Example 2 also shows that during the aging process from 500℃ to 700℃, the resistivity of the gold-based alloy electrical contact sheet decreases. At this temperature, the precipitation of solute atoms reduces lattice distortion and dislocation scattering, and its effect on increasing resistivity is stronger than the effect of interfacial scattering introduced by the precipitated phase on reducing resistivity. Ultimately, this achieves a strengthening effect in reducing resistivity. Thus, at an aging temperature of 700℃, the solute content is lowest, the lattice temperature is highest, and the resistivity reaches its minimum value. When the aging temperature increases to 800℃, the increase in precipitated phases leads to interfacial scattering becoming dominant, causing an increase in resistance. The resistivity of the gold-based alloy electrical contact sheet shows a slight increase, and further increases in temperature will cause a further increase in resistivity. Therefore, this invention controls the aging temperature within the range of 600-800℃, which is beneficial for maintaining the conductivity of the gold-based alloy electrical contact sheet at an optimal level.

[0099] pass Figure 4 It can be seen that the electrical contact sheet prepared by this invention forms a continuous nanoscale precipitate phase with an L12 ordered structure. These ordered precipitates help to distribute dislocation buildup, increase stress levels, and improve elastic properties, thereby achieving a better balance between the tensile strength and plastic deformation capacity of the gold-based alloy electrical contact sheet, and significantly improving the wear resistance and machinability of the gold-based alloy electrical contact sheet.

[0100] In summary, this invention effectively improves the tensile strength, wear resistance, and conductivity of gold-based alloy electrical contacts by synergistically optimizing the composition and preparation method of the gold-based alloy. This allows the gold-based alloy electrical contacts to achieve an optimal balance of mechanical properties, possessing both excellent wear resistance and conductivity. Consequently, the overall performance of the gold-based alloy electrical contacts is at a superior level, meeting the requirements of demanding working conditions.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A gold-based alloy electrical contact piece, characterized in that: The gold-based alloy electrical contact sheet comprises, by weight percentage: palladium: 25%-30%, silver: 15%-20%, tin: 1%-5%, with the balance being gold.

2. The method for preparing the gold-based alloy electrical contact sheet according to claim 1, characterized in that: The preparation method includes the following steps: (1) Palladium, silver, tin and gold raw materials are mixed and smelted in an inert gas protective environment, and then cast to obtain ingots; (2) Perform solution treatment on the ingot in step (1); (3) The ingot after solution treatment in step (2) is cold-forged multiple times to obtain a plate; (4) In an inert atmosphere, the plate in step (3) is hot rolled in multiple passes to obtain a hot rolled billet. After each hot rolling pass, the hot rolled part is kept warm. (5) The hot-rolled billet in step (4) is annealed in an inert atmosphere to obtain an annealed billet. (6) After the annealed billet in step (5) is subjected to multiple cold rolling and aging treatments, a sheet is obtained. During the multiple cold rolling process, a low-temperature tempering is performed after every 5-8 rolling passes. The aging treatment is carried out in an inert atmosphere protection environment. (7) The sheet material in step (6) is subjected to surface treatment to obtain a gold-based alloy electrical contact sheet.

3. The preparation method according to claim 2, characterized in that: In step (1), the melting temperature is 1300-1400℃ and the melting time is 10-15min.

4. The preparation method according to claim 2, characterized in that: In step (2), the solution temperature is 1140-1160℃, the holding time is 3.5-4h, and after holding, water quenching is performed with a cooling rate ≥200℃ / s.

5. The preparation method according to claim 2, characterized in that: In step (3), the deformation amount of a single cold forging is ≤5%, and the cumulative deformation amount of cold forging is 50-75%.

6. The preparation method according to claim 2, characterized in that: In step (4), the plate is heated to 700-750℃, held for 40-60 minutes, and then hot rolled while maintaining the temperature. After each hot rolling pass, the plate is held at 700-750℃ for 5-10 minutes. The deformation of a single pass in multi-pass hot rolling is ≤5%, and the total deformation of multi-pass hot rolling is 40-60%.

7. The preparation method according to claim 2, characterized in that: In step (5), the annealing temperature is 900-1000℃, the holding time is 15-20min, and after holding, the water is quenched with a cooling rate ≥200℃ / s.

8. The preparation method according to claim 2, characterized in that: In step (6), the deformation amount of a single pass in multi-pass cold rolling is 3-5%, the cumulative deformation amount is 50-75%, the low-temperature tempering temperature is 150-200℃, and the tempering time is 10-20min.

9. The preparation method according to claim 2, characterized in that: In step (6), the aging treatment temperature is 600-800℃, the holding time is 50-60min, and after holding, the water is quenched with a water quenching rate ≥200℃ / s.

10. The preparation method according to claim 2, characterized in that: In step (7), the surface treatment process specifically includes: firstly, using saturated saline or saturated hydrochloric acid as the electrolytic polishing solution to electrolytically polish the sheet, with the electrolytic polishing temperature being 15-25℃ and the current density controlled at 3-5A / dm² according to the sheet area. 2 Then, ultrasonic cleaning and vacuum drying are performed in sequence.

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